Plasma display panels (PDPs) can be broadly divided into direct current (DC) and alternating current (AC) types. However, AC PDPs are currently the major focus of attention due to their suitability for large-screen application.
Conventional AC-type surface discharge PDPs that conduct RGB color image display, as well as related drive methods are disclosed, for example, in Japanese publication of unexamined applications No. 6-186927 and No. 5-307935. The disclosed technology is basically as follows.
A conventional PDP is structured from a front cover plate and a back plate that are disposed parallel to each other and with a gap therebetween. On the front cover plate, display electrodes (i.e. scan electrodes and sustain electrodes) are arranged in a stripe pattern, and a dielectric layer is provided so as to cover these electrodes. On the back panel, data electrodes and barrier ribs are arranged in a stripe pattern that is orthogonal to the display electrodes, and between the barrier ribs are arranged ultraviolet light excitation phosphor layers corresponding to the colors red, green and blue. Between the two plates, cells are formed where the electrodes extend across each other orthogonally, and a discharge space within each cell is filled with a discharge gas.
According to a conventional drive method, firstly, in an initialization period, an initialization discharge is generated in all of the cells within the panel by applying an initialization pulse to the scan electrodes. The initialization discharge serves to equilibrize the space charge throughout the panel, and to accumulate wall charge (i.e. effective when a write discharge is subsequently generated) in a vicinity of the data electrodes.
Next, in a write period, a write discharge is generated in cells to be turned on (hereafter, “on-cells”) by applying a positive data pulse selectively to the scan electrodes at the same time that a negative scan pulse is applied sequentially to the scan electrodes. Here, the write discharge generally induces a write sustain discharge to generate between the scan electrode and the sustain electrode in the on-cells, thus completing the writing.
Next, in a sustain period, a high voltage sustain pulse is applied alternately to the scan electrode and the sustain electrode in the on-cells. In this way a discharge is selectively repeated in the written cells, and image display is achieved as a result of the luminescence that arises from this sustain discharge. Then, in an erase period, the wall charge stored on the dielectric as a result of the sustain discharge is erased by erase pulses applied to the sustain electrodes.
With respect to PDP design, the present task is to improve the luminescence brightness in a PDP having the above structure.
However, in order to improve luminescence brightness, it is desirable to lengthen the sustain period as much as possible by shortening the initialization, write and erase periods, since the sustain period is the only period that actually contributes to luminescence in the cells.
To shorten the write period, a pulse width of the scan pulse applied to the scan electrodes and the data pulse applied to the data electrodes is preferably shortened as much as possible. Currently, there is an increasing demand for display devices capable of high definition image display, and attempts are being made to keep the aforementioned pulse widths to around 1.0 μsecs or less in order to conduct effective writing without having to extend the length of the write period.
However, a certain amount of dispersion occurs from the time that application of the scan and data pulses is commenced until the time that a discharge is generated, and thus shortening the pulse widths of the scan and data pulses increases the possibility that defective writing will occur.
Since the occurrence of defective writing results in the on-cells not being turned on, the quality of the displayed image is consequently reduced.